激光熔覆FeCrMoCBY非晶合金梯度涂层的组织与摩擦学性能研究

Microstructure and Tribological Properties of FeCrMoCBY Amorphous Alloy Gradient Coating Prepared by Laser Cladding

摘要:

为提高铁基非晶合金涂层的非晶相含量与摩擦学性能，本工作提出在45#钢基板上制备铜合金/非晶梯度涂层的新策略。采用同步送粉激光熔覆技术，分别制备单层FeCrMoCBY非晶涂层及铜合金（CuSn12Ni2）/非晶双层梯度涂层，系统研究激光扫描速率（2000~4000 mm/min）对涂层微观结构、非晶相形成及摩擦学性能的影响。结果表明：铜合金/非晶双层梯度结构通过铜层的高导热性显著加速熔池冷却，降低非晶形成的临界冷却速率需求，从而大幅提升非晶相含量，达68.9wt%~92.3wt%，较单层涂层提升显著，其中扫描速率3000 mm/min时非晶相含量最高（92.3wt%）。涂层中析出M₂₃C₆型碳化物亚微米晶，弥散分布于非晶基体，通过钉扎效应提升硬度。梯度涂层平均显微硬度超1000 HV_0.1（峰值1288.75 HV_0.1，达基材6倍），且发现适度晶化可强化材料硬度。非晶合金涂层磨损机制以磨粒磨损为主导，高硬度导致脆性剥落形成磨屑，引发二次犁沟。本研究证实梯度结构通过铜合金中间层的热传导调控作用，为非晶相形成提供了更优的热力学条件，为高非晶含量耐磨涂层的工程应用提供新思路。

Abstract:

To enhance the amorphous phase content and tribological properties of iron-based amorphous alloy coatings, this study proposed a novel strategy for fabricating copper alloy/amorphous gradient coatings on 45# steel substrate. Using coaxial powder-feeding laser cladding technique, single-layer FeCrMoCBY amorphous coatings and copper alloy (CuSn12Ni2)/amorphous double-layer gradient coatings were separately prepared. The effects of laser scanning speed (2000–4000 mm/min) on the microstructure, amorphous phase formation, and tribological properties of the coatings were investigated. The results show that the copper alloy/amorphous double-layer gradient structure significantly accelerates molten pool cooling via the high thermal conductivity of the copper interlayer, reducing the critical cooling rate requirement for amorphous formation. Consequently, the amorphous phase content is substantially improved to 68.9wt%–92.3wt%, showing a remarkable enhancement compared to the single-layer coating. The highest amorphous phase content (92.3wt%) is achieved at a scanning speed of 3000 mm/min. M₂₃C₆-type carbide submicron crystals precipitate in the coating and are dispersedly distributed in the amorphous matrix, improving the hardness through a pinning effect. The average microhardness of the gradient coating exceeds 1000 HV_0.1 (peak value of 1288.75 HV_0.1, which is six times higher than that of the substrate). It is also found that moderate crystallization can enhance hardness of the material. The wear mechanism of the amorphous alloy coating is dominated by abrasive wear. High hardness leads to brittle spallation and the formation of wear debris, which induces secondary ploughing. This study demonstrates that the gradient structure provides more favorable thermodynamic conditions for amorphous phase formation through the thermal-conductivity regulation effect of the copper alloy interlayer, offering new insights for the engineering application of wear-resistant coatings with high amorphous phase content.